Spark plug



June 9, 1925. 1,541,633

A. F. FARMAN SPARK rum Fileduan- 1923 v WITNESS INVENTOR AJ. FARM/IN ATTORNEY- Patented June 9, 1925.

UNITED STATES ARTHUR 1. FARHAN, OF OAKLAND, CALIFORNIA. I

I SPARK PLUG.

Application filed January 2, 1928. seriall'o. 810,182.

vide simple means for electrically heating the plug and which may be arranged directly within and readily incorporated with practically any of the ordinary types of spark plug.

features of advantage, some of which, with the fore oing, will be set forth in the following escription of the referred form of my invention which is i lustrated in the drawing accompanying and forming part of the specification. It is to be understood that I do not limit myself to the showing made by the said drawing and description,

as I ma adopt variations of the pre erred form within the scope of my invention as set forth in the claim.

Referring to said drawing:

The figure is a artly sectional view of a spark plug provi ed with one form of the heating means of my invention.

The d'ifiiculties attending the task pf starting an internal combustion engine when the surrounding temperature is comparatively low are well known, and as heretofore stated it is one of the chief aims of the present invention to eliminate this annoying feature. I have found that by heating the explosive mixture within the spark plug or adjacent thereto or both, prior to attempting to ex lode said mixture, that practically no difiicu ty is encountered in starting engines of large size and under extremely unfavorable conditions as to temperature. In accordance with the foregoing I have therefore inco rated with the ordinary spark plug suita 1e means for pre-heating the explosive mixture adjacent the ignition arc.

The invention possesses other objects and Briefly expressed the structure as here shown comprises the usual bushing provided with one of the electrodes and in which is arranged the insulating core containing the central electrode. The heating element consists of a coil which encircles the insulating core, is grounded at oneextremity, and is connected at its other extremity to a source of electrical energy by means of a novel connection insulated from but supported by the bushing.

A detailed description follows:

The invention in its present embodiment is shown in connection with an ordinary spark plug 2 having a bushing'3 suitably threaded for enabling it to be screwed into the cylinder head of an internal combustion engine, and provided atits lower extremity with the usual electrode'4. The core 6, generally formed of porcelain or similar insulating material, is removabl arranged within the bushing and is provi ed with the electrode centrally disposed therein. The plug is also provided with the usual gland 8 and packing rings 9 which engage the core adjacent the shoulder 12.

Preferably arranged on the core 6 is a heating element 13 which as here shown is in the form of a coil 14 encircling the core and adapted to be heated to a comparatively high temperature by having a current of electricity passed'through it. On end 16 of the coil is preferably grounded'by connecting it to one of the metallic packin rings 9, whereas the other end 17 is attac ed to a metallic collar 18 in contact with a, spring element 19 formed on the inner extremity of the post 21, the connection between the collar and post thus insuring the proper electrical contact and at the same time permitting of the unhampered withdrawal or.insertion of the core. Thepost 21 is suitably'insulated from and supported by the bushing 3, and is connected by a lead 22 toa convenient source ofelectric current such as a battery 23. The lead 22 is provided with a switch 24 for opening or closing the circuit.

It will now be understood that with the use of my invention, by throwing the switch to heat the coil for a comparativel short space of time, the engine will or inarily start without any difficulty.

I claim:

Q 1,541,0ss

A spark plug comprisingabushing, an intact mounted on and insulated from said sulating core removably positioned therein, bushing and arranged to engage said con- 10 an electric heating element arranged on the ductor. outer side said core and having one ter- In testimony whereof, I have hereunto set 5 minal electrically connected to 881d bushing, my hand at Oakland, this 15th day of Dea conductor electrically connected to the cember, 1922. other terminal of said element and encircling said core on its exterior, and a resilient con- ARTHUR F. FARMAN. 

